Portable medical devices are useful for patients that have conditions that must be monitored on a continuous or frequent basis. For example, diabetics are usually required to modify and monitor their daily lifestyle to keep their body in balance, in particular, their blood glucose (BG) levels. Individuals with Type 1 diabetes and some individuals with Type 2 diabetes use insulin to control their BG levels. To do so, diabetics routinely keep strict schedules, including ingesting timely nutritious meals, partaking in exercise, monitoring BG levels daily, and adjusting and administering insulin dosages accordingly.
The prior art includes a number of fluid infusion devices and insulin pump systems that are designed to deliver accurate and measured doses of insulin via infusion sets (an infusion set delivers the insulin through a small diameter tube that terminates at, e.g., a cannula inserted under the patient's skin) In lieu of a syringe, the patient can simply activate the insulin pump to administer an insulin bolus as needed, for example, in response to the patient's current BG level.
A typical infusion pump includes a housing, which encloses a pump drive system, a fluid containment assembly, an electronics system, and a power supply. The pump drive system typically includes a small motor (DC, stepper, solenoid, or other varieties) and drive train components such as gears, screws, and levers that convert rotational motor motion to a translational displacement of a stopper in a reservoir. The fluid containment assembly typically includes the reservoir with the stopper, tubing, and a catheter or infusion set to create a fluid path for carrying medication from the reservoir to the body of a user. The electronics system regulates power from the power supply to the motor. The electronics system may include programmable controls to operate the motor continuously or at periodic intervals to obtain a closely controlled and accurate delivery of the medication over an extended period.
Personal medical devices such as infusion pumps are typically powered by a battery or battery pack. For example, some medical devices can be powered by a single AA battery. The portable nature of such devices means that they might be subjected to physical impact, shock, or stress (which may result from physical activity of the user, accidental bumping into nearby objects, dropping of the device, etc.). The force imparted by a battery to the housing of a portable medical device could compromise the integrity of the housing and/or disturb the delicate operating components inside the housing. Accordingly, it is desirable to have a feature or component that protects the battery, the housing, and/or other elements of a medical device from battery impacts.
A number of electronic devices, including personal medical devices such as infusion pumps, include membrane keypad assemblies that allow the user to manipulate certain functions of the devices. Conventional membrane keypad assemblies usually include an underlying keypad layer and an overlying actuator layer. The bottom surface of the actuator layer is typically printed with graphics associated with the different keys or buttons and/or with decorative graphics. The actuator layer is usually attached to the keypad layer or the housing of the device using an adhesive or bonding material. Ideally, the actuator layer is sealed around the housing such that moisture and contaminants cannot enter the housing. Indeed, some personal medical devices are designed to be water resistant (to accommodate bathing, swimming, exposure to rain, etc.) and, for such devices, the actuator layer forms a water resistant seal with the housing. In this regard, it is desirable to have a membrane keypad assembly that exhibits strong, robust, and reliable water resistant characteristics.
Many electronic devices, including personal medical devices such as infusion pumps, use piezoelectric speakers to generate sound. If the device is waterproof or water resistant, then a piezoelectric speaker will typically be mounted against the inner wall of the housing for purposes of transmitting sound to the outside world. For such implementations, the volume of sound produced by the piezoelectric speaker will be influenced by various factors such as the shape, size, and structural features of the housing. If a piezoelectric speaker is mounted directly to a rigid case or housing of a device, however, it will not effectively or efficiently generate sound at the desired volume. Accordingly, it is desirable to have a piezoelectric speaker assembly that operates effectively when mounted within a sealed rigid housing of an electronic device.